// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2010-2011 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#include "lapack_common.h"
#include <Eigen/Cholesky>

// POTRF computes the Cholesky factorization of a real symmetric positive definite matrix A.
EIGEN_LAPACK_FUNC(potrf, (char* uplo, int* n, RealScalar* pa, int* lda, int* info))
{
	*info = 0;
	if (UPLO(*uplo) == INVALID)
		*info = -1;
	else if (*n < 0)
		*info = -2;
	else if (*lda < std::max(1, *n))
		*info = -4;
	if (*info != 0) {
		int e = -*info;
		return xerbla_(SCALAR_SUFFIX_UP "POTRF", &e, 6);
	}

	Scalar* a = reinterpret_cast<Scalar*>(pa);
	MatrixType A(a, *n, *n, *lda);
	int ret;
	if (UPLO(*uplo) == UP)
		ret = int(internal::llt_inplace<Scalar, Upper>::blocked(A));
	else
		ret = int(internal::llt_inplace<Scalar, Lower>::blocked(A));

	if (ret >= 0)
		*info = ret + 1;

	return 0;
}

// POTRS solves a system of linear equations A*X = B with a symmetric
// positive definite matrix A using the Cholesky factorization
// A = U**T*U or A = L*L**T computed by DPOTRF.
EIGEN_LAPACK_FUNC(potrs, (char* uplo, int* n, int* nrhs, RealScalar* pa, int* lda, RealScalar* pb, int* ldb, int* info))
{
	*info = 0;
	if (UPLO(*uplo) == INVALID)
		*info = -1;
	else if (*n < 0)
		*info = -2;
	else if (*nrhs < 0)
		*info = -3;
	else if (*lda < std::max(1, *n))
		*info = -5;
	else if (*ldb < std::max(1, *n))
		*info = -7;
	if (*info != 0) {
		int e = -*info;
		return xerbla_(SCALAR_SUFFIX_UP "POTRS", &e, 6);
	}

	Scalar* a = reinterpret_cast<Scalar*>(pa);
	Scalar* b = reinterpret_cast<Scalar*>(pb);
	MatrixType A(a, *n, *n, *lda);
	MatrixType B(b, *n, *nrhs, *ldb);

	if (UPLO(*uplo) == UP) {
		A.triangularView<Upper>().adjoint().solveInPlace(B);
		A.triangularView<Upper>().solveInPlace(B);
	} else {
		A.triangularView<Lower>().solveInPlace(B);
		A.triangularView<Lower>().adjoint().solveInPlace(B);
	}

	return 0;
}
